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Date: Tue, 09 Jan 2001 19:52:02 -0500
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
From: "Peter J. Farley III" <pjfarley AT banet DOT net>
Subject: Re: Fw: Patch for statfs.c
Cc: djgpp-workers AT delorie DOT com, Martin Str|mberg <ams AT ludd DOT luth DOT se>,
        ceo AT nbensacomputers DOT com
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At 10:03 AM 1/9/01 +0200, Eli Zaretskii wrote:
<Snipped>
 >Does the version in fil316s.zip differ from what's in stock v2.03
 >libc?  If so, it's possible that you are right (I didn't build the
 >current fil316b.zip on SimTel, so I don't know for sure).

Yes, but only in seemingly minor ways.  Here are the two versions:

N:\>dir o:\gnu\filutil3.16\djgpp\statfs.c
<Other dir stuff snipped>
  Directory of O:\gnu\filutil3.16\djgpp

STATFS   C           4,707  03-29-97 11:48a statfs.c
          1 file(s)          4,707 bytes
          0 dir(s)     633,094,144 bytes free

N:\>dir statfs.c
<Other dir stuff snipped>
  Directory of N:\

STATFS   C           4,797  08-04-99  3:58p statfs.c
          1 file(s)          4,797 bytes
          0 dir(s)   1,290,010,624 bytes free

Here is the diff command I ised to see what was different:

N:\>diff -u o:/gnu/filutil3.16/djgpp/statfs.c statfs.c>statfs97.dif

And here is the result of the diff:

=========statfs97.dif================
--- o:/gnu/filutil3.16/djgpp/statfs.c	Sat Mar 29 11:48:10 1997
+++ statfs.c	Wed Aug  4 15:58:24 1999
@@ -1,14 +1,16 @@
+/* Copyright (C) 1999 DJ Delorie, see COPYING.DJ for details */
+/* Copyright (C) 1998 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 1997 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
+#include <libc/stubs.h>
+#include <string.h>
  #include <dpmi.h>
  #include <go32.h>
-#include <sys/movedata.h>
+#include <libc/farptrgs.h>
  #include <errno.h>
-#include <string.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <sys/vfs.h>
-#include <libc/farptrgs.h>
  #include <libc/dosio.h>

  int
@@ -19,10 +21,11 @@
    int cdrom_calls_used = 0;
    int blocks = 0;

-  /* Get the drive number */
-  if (path[0] && path[1] == ':')
-    drive_number = (path[0] & 0x1f) - 1;
-  else
+  /* Get the drive number, including the case of magic
+     names like /dev/c/foo.  */
+  _put_path(path);
+  drive_number = (_farpeekb(_dos_ds, __tb) & 0x1f) - 1;
+  if (_farpeekb(_dos_ds, __tb + 1) != ':' || drive_number == -1)
    {
      regs.h.ah = 0x19;
      __dpmi_int(0x21, &regs);
=========statfs97.dif================

 >In any case, I think we need to understand the cause for the
 >discrepancy, because it might provide us with the solution to the
 >problem of slightly incorrect size.
 >
 >> Can objdump be used to extract just one function's code from an
 >> executable?
 >
 >What do you mean by that?  Do you want to see the disassembly of a
 >single function?

Yes.

 >> If we could extract just the statfs function, we could
 >> diff the output of objdump of the statfs code from the distributed
 >> binary and the current libc version of statfs to see how they are
 >> different.
 >
 >That won't be easy, I'm afraid: differences in compiler and Binutils
 >versions and switches can produce changes on the assembly level that
 >completely obscure the real code differences.

Oh well, it was just an idea.

 >It is much easier to try several avaiable versions of statfs, since
 >the number of these versions is small (like 3 or something).

Agreed, that seems to be the only way.  The problem is, I can't get any 
of the versions I've tried so far to give the results that df from 
fil316b.zip gives.  I will try building fil316s.zip with the stock 
v2.03 libc.a and see what results I get from that.  It's the only one I 
haven't tried yet.

---------------------------------------------------------
Peter J. Farley III (pjfarley AT dorsai DOT org OR
                      pjfarley AT banet DOT net)